1. Field of the Invention
Although technology advancement has made real progress today, from past to present, mailing letters will not likely cease in the near future. The mail system is still the most widely and economical communication method. For a long time, envelopes have not been altered much, except for a small number of styling changes made such as a window, longer or curved cover flap, etc. Regarding envelope opening structure, only additions of a metal clasp or a cotton string closure or a self-adhesive cover flap have been introduced. But with regard to reopening envelope after it has been sealed, no effective improvement or progression has been made obvious.
2. Description of the Prior Art
Recently, some other inventors have come up with envelopes having a cover flap folding line including a cotton string or glue fixture in addition to a cotton string, or a free end of the cotton string, which when pulled, opens the envelope. These inventions include:
A. 1985 Japan Patent numbers 60-27029 & 60-27030 PA1 B. 1911 England Patent number 25047 PA1 C. 1936 England Patent number 185157 PA1 D. 1937 England Patent number 187443 PA1 E: 1984 England Patent number 2160172 PA1 F. 1986 England Patent number 2190064 PA1 G. 1986 England Patent number 2190353 PA1 H. 1989 England Patent number 2217682 PA1 I. 1930 England Patent number 350700 PA1 1. Gluing and arranging the cotton string along a folding line of a cover flap of an envelope at the same time is difficult to do. PA1 2. Both the process of gluing and arranging the cotton string can not be accomplished by machinery in one step and, therefore, are not economical. PA1 3. It is easy to cause a separation between the cotton string and the cover flap when the cotton string is pulled, thereby disrupting the envelope opening procedure. PA1 4. The free end of the cotton string exposed outside of the envelope may cause mail to be opened by mistake during the delivering process. PA1 A. 1948 France Patent number 937010 PA1 B. 1975 Swiss Patent number 564919
But obvious shortcomings of these methods are:
Another line of envelope inventions having a cover flap folding line consists of a tear thread exposed at one corner of the envelope, which when pulled toward the opposite end, opens the envelope, for instance:
These designs appear to solve the problem of inadvertent opening of the envelope caused by a separation of the cover flap and cotton string. However, they are difficult to quickly manufacture because every cover flap folding line must be completely sewn with tearing thread. These designs, while useful, are not ideal, and as a result, the present invention was conceived.
The present invention relates to a type envelope which can be easily opened. The main feature of the invention is that it can be applied to either vertical or horizontal layout envelopes. For vertical layout envelopes (Oriental style), lines of perforations are set to overlap the folding lines on the top and bottom cover flaps. For horizontal layout envelopes (Western style), a line of perforations is set to overlap one of the four folding lines of cover flaps. Furthermore, a 2 to 3 mm wide tenacious self-adhesive tearing band is fastened to the line of perforations and intersects with an angled tearing line. To open the user simply tears the angled tearing line and lightly pulls the tearing band along the line of perforations towards the opposite end, thereby allowing the tenacious self-adhesive tearing band to break free from the line of perforations and effectively cut the envelope open along the line of perforations. The present invention has characteristics including ease of manufacture, ease of use and high reliability against preventing unintentional opening.